Fluorescent lighting fixtures, sometimes termed "luminaires", are widely used in business, factory and residential lighting applications. Presently, the most common type of fixture is the modular 2' by 4' fixture recessed as part of a suspension system or surface mounted on a ceiling. Fixtures of this type have two to four lamps with four lamps being most common. In accordance with conventional construction, two pairs of fluorescent lamps are each connected in series and each activated by a common ballast. Generally one ballast controls the two outer lamps and another ballast controls the inner two lamps. The lamps are disposed in parallel arrangement within a metal housing or frame sometimes termed a "troffer". A diffuser or lens of translucent or transparent material extends across the opening of the fixture below the fluorescent lamp tubes.
The Energy Policy Act of 1992 is a comprehensive bill having lighting energy efficiency provisions which prohibits production of certain lamps. As a result of the requirements of building owners and facility managers for high performance lighting and further due to the impact of EPAC, many users are turning to "high efficiency compact fluorescent lighting systems." These systems utilize shorter two foot U-shaped fluorescent lamps. These lamps, as the more conventional older systems, are often mounted in an enclosure and are connected to a ballast very similar to the construction of the older systems. The newer luminaires are often smaller, often being only 2'.times.2' as compared to the longer 4' older fixtures.
A significant problem common to both the older fluorescent systems and the newer compact systems is convenience of installation and accessibility for maintenance when it becomes necessary to replace a burned out or non-functioning ballast or lamp. Generally replacement of a ballast requires that the maintenance person first remove the lamps and then remove a panel which is held in place by tabs or mechanical fasteners to gain access to the ballast. This procedure is time consuming. Similarly, initial installation often requires several separate installation tasks which have to be coordinated between several trades including an installer and an electrician.
There are various fixtures in the prior art which are designed to provide improved access to the fixture are designed to facilitate more efficient installation and maintenance.
For example, U.S. Pat. No. 3,240,928 relates to a lighting fixture which enables detachment of a lamp reflector housing from a separate ballast chamber and which does not require removal of the ballast chamber from the support structure. The lamp and ballast chambers are separate and each have removable or hinged lids for ease of servicing.
U.S. Pat. No. 4,342,072 shows a lighting fixture with a housing having a pair of supporting members disposed longitudinally along the inner portion of the wall to slidingly engage the circuitry and a light carrying tray. According to the patentee, routine maintenance such as changing a light or ballast transformer does not involve any substantial disassembly.
U.S. Pat. No. 4,870,549 shows a ceiling light which has a projection in the form of a lid pivotally mounted to the housing base into which the electrical components are attached. During the insertion of the light housing, the lid together with the electrical components can be pivoted through a rectangular opening in a side wall of the housing.
U.S. Pat. No. 5,274,533 discloses a reflector assembly in which access to the ballast of the luminaire is improved by providing a removable section of the reflector assembly located over the ballast.
Despite attempts made in the prior art to provide an improved and more installation and maintenance friendly light fixture designs, there nevertheless remains a need for an improved light fixture of this type.